Sheep and cattle are prone to bacterial hoof infections that can be quite debilitating. A common condition in cattle is “foot rot” or what is medically termed interdigital phlegmon. It is an infection of the soft tissue between the claws of the feet and is caused by two anaerobic bacteria, Fusobacterium necrophorum and Prevotella melaninogenicus (formerly known as Bacteroides melaninogenicus). These bacteria are common in the environment and F. necrophorum is present in the rumen and feces of normal cattle. Once these bacteria invade the skin of the foot, they rapidly cause the condition we recognize as foot rot. Injury or damage to the skin between the claws allows this invasion to occur. Common factors that can cause damage of this sort include stubble fields, small rocks and pebbles, and abrasive surfaces. Additionally, high temperatures and excess moisture or humidity causes the skin between the claws to chap and crack allowing these bacteria to invade.
Ovine foot rot is caused by an interaction of two anaerobic, Gram (−) bacteria, Dichelobacter nodosus (formerly known as Bacteroides nodosus and Fusiformis nodosus) and Fusobacterium necrophorum. Fusobacterium necrophorum is a normal inhabitant of the ruminant digestive tract and in wet weather may interact with another bacteria, Corynebacterium pyogenes, to produce foot scald, an infection of the skin between the toes. This infection sets up the foot for invasion by D. nodosus, which produces the condition referred to as foot rot.
Farmers typically take steps to avoid foot rot. One common practice is to utilize a foot bath for the sheep or cows. This is not only an effective preventive measure, it is an effective treatment for such bacterial infections.
There are two different types of solutions commonly used in foot baths: zinc sulfate and copper sulfate. For treatment, they should be used 1-2 times per week for several weeks. They may also be used routinely after foot trimming and as a preventative. Predominantly, copper sulfate is the solution of choice for treating foot rot, particularly with cattle. Zinc sulfate, although somewhat effective, has shown mixed results.
The use of copper sulfate presents environmental concerns. The foot bath solution is typically drained into the manure store and is subsequently applied to the fields. Excess copper can be hazardous to the cattle and sheep. The application of the copper-laden manure onto the fields causes a copper build-up, which can be problematic to the plants' development and, therefore, should be avoided.
Zinc sulfate does not have this problem. However, as indicated, it is not as well accepted nor considered to be as effective as copper sulfate. Further, zinc sulfate and copper sulfate are acidic in solution. A more acidic treatment reduces the desired contact time. This reduces efficacy. Other treatments, such as the use of formalin have other disadvantages.